The present invention relates to a method and apparatus for monitoring the application of dye to textile material and, more particularly, to a method and apparatus for monitoring the application of dye to a traveling web of textile material.
It is known to detect a color characteristic of a web of textile material very shortly after the web has been subjected to a dye application process in which dye has been applied to the web to impart the desired coloring thereto. For example, German Patent Document DE-OS 39 25 444 discloses an apparatus which detects a color characteristic of a traveling web of textile material immediately after the web has emerged from a dye liquor bath in which dye has been applied to the web. The detecting arrangement disclosed in this document directly measures a color characteristic of the traveling web of textile material as opposed to indirectly measuring a color characteristic by, for example, measuring the moisture content of the web and extrapolating information from such a measurement regarding the color characteristic of the web. As the detecting of the color characteristic of the web is typically performed at a location along the web travel path only a few meters beyond the dye application location, this known detecting arrangement provides relatively rapid feedback concerning the color characteristic of the web. Accordingly, if it is detected that the color characteristic of the web is not within acceptable limits, immediate corrections, including shutdown of the travel of the web, can be implemented to prevent the following portions of the web from also being handled such that they, too, are imparted with an improper color characteristic.
While the known detecting arrangement discussed above readily lends itself to incorporation into an automatic control system which automatically controls the travel of the web, as well as other parameters of the web handling process such as, for example, the removal of excess moisture from the web, such a detecting arrangement is not capable of detecting an out-of-limits color characteristic situation which is only detectable after the web has already traveled past the detecting position at which the detecting arrangement operates. For example, an out-of-limits color characteristic of the web may not be detectable until after the web has been handled in a drying process which takes place further downstream from the detecting location. Accordingly, the need exists for a method and apparatus which provides the capability to monitor the application of dye to a traveling web of textile material in such a manner that an out-of-limits color characteristic situation of the web can be detected and automatically taken into account in handling the web.